What Do You Want to Know (about history)? Wolfram Alpha and the Computational Knowledge Engine.
Wolfram Alpha lets users interact with over 10 trillion pieces of information curated by a large research team. You just type in what you want to know, the engine tries to figure out what you’re asking it, and you’re presented with a remarkable array of information (as well as ways to refine your subsequent searches). This has tremendous historical applications, both for teaching and for historical research.